Posted: | Categories: JavaScript, Programming
Here’s a little JavaScript function that disables all form elements:
function disableElements(formName) {
var fm = document.forms[formName];
for(var i = 0; i < fm.elements.length; ++i) {
fm.elements[i].disabled = true;
}
}As you may have noticed the only parameter you need to pass is the form name.
Read more...Posted: | Categories: JavaScript, Programming | Tags: RegExp
There are whole books about regular expressions so this post shouldn’t be intended as an exhaustive resource on the subject. It just shows how to extract a substring from a string using regular expressions in JavaScript so it must be considered just a tip not a tutorial on RegExp. Look at the following example:
var str = "https://www.alessandrolacava.com/?code=ALE69";
var regex = /code=(w+)&?/;
var results = regex.exec(str);
if(!results){
alert("no match");
}
else{
// first group
alert(results[1]);
}The previous code extracts the string that follows the code= part of str. That string is captured in the first group. of the RegExp, that’s why I use results[1] to display it. When you utilise groups–through the use of parenthesis ()–you can refer to them using indices, starting from 1. Indeed, at the index 0 you find the whole match. In the previous example, results[0] is equal to code=ALE69
Posted: | Categories: JavaScript, Programming | Tags: Timestamp
Many sources use the term timestamp to refer specifically to Unix time, the number of seconds since 00:00:00 UTC on January 1, 1970. In JavaScript you can use the built-in object Date to compute this timestamp. Here follows an example:
var ts = Date.UTC('2007', '09', '28') / 1000;
alert(ts);The previous code displays an alert with the number of seconds between 00:00:00 UTC on January 1, 1970 and 00:00:00 UTC on October 28, 2007.
Read more...Posted: | Categories: JavaScript, Programming
In JavaScript you can use a built-in method to format a decimal number so that it is displayed using, at most, x decimal places. Here is an example:
var num = 3.1356;
var x = 3;
alert(num.toFixed(x)); // displays 3.136
As you may have guessed the method is toFixed. It accepts one parameter which is the number of decimal places
to take into account.
Note: The number gets rounded as you can notice by the example above.
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